Why a rotten tooth is hard to find
Brain can't distinguish pain coming from top versus bottom tooth
When it comes to a toothache, the brain doesn’t discriminate. A new imaging study shows that to the brain, a painful upper tooth feels a lot like a painful lower tooth. The results, which will be published in the journal Pain, help explain why patients are notoriously bad at pinpointing a toothache.
For the most part, humans are exquisitely tuned to pain. The brain can immediately distinguish between a splinter in the index finger and a paper cut on the thumb, even though the digits are next-door neighbors. But in the mouth this can be more difficult, depending where and how intense the ache is.
“We don’t know much about tooth pain,” comments dentist and neuroscientist Alexandre DaSilva of the University of Michigan in Ann Arbor, who was not part of the new research. The new study is one of the first to address the puzzle of toothache localization, he says.
In the study, researchers led by Clemens Forster of the University of Erlangen-Nuremberg in Germany analyzed brain activity in healthy — and brave — volunteers as they experienced tooth pain. The researchers delivered short electrical pulses to either the upper left canine tooth (the pointy one) or the lower left canine tooth in the subjects. These bursts of electrical stimulation produced a painful sensation similar to that felt when biting into an ice cube, Forster says, and were tuned such that the subject always rated the pain to be about 60 percent, with 100 percent being the worst pain imaginable.